Mayweather announces Alvarez fight on Twitter

Undefeated WBC welterweight champion Floyd Mayweather Jr. attends a news conference at the MGM Grand Wednesday, May 1, 2013. Mayweather will defend his title against Robert Guerrero at the MGM Grand Garden Arena on Saturday.

Floyd Mayweather tweeted that he will fight Mexican star Canelo Alvarez on Sept. 14 at the MGM Grand.

"I chose my opponent for September 14th and it's Canelo Alvarez," Mayweather said Wednesday night on Twitter. "I'm giving the fans what they want. It will be at the MGM Grand."

Alvarez sent a tweet in Spanish announcing the fight.

Mayweather is unbeaten in 44 fights, the last a unanimous 12-round decision over Robert Guerrero on May 4 in a welterweight title fight. Alvarez is 42-0-1. He unified the WBC and WBA super welterweight titles April 20 in San Antonio with a unanimous victory over Austin Trout.

Demetrious "Mighty Mouse" Johnson slammed his hands down on his UFC flyweight championship belt. Somewhere else in Rogers Arena, Rory MacDonald surely looked on with envy. Johnson and MacDonald put on dominant performances in the UFC's first trip to Vancouver in three years. Johnson defended his title for the fourth time, not allowing Ali Bagautinov to win any of their five fast-paced rounds. That couldn't quite top MacDonald, who barely let Tyron Woodley touch him in an all-important welterweight co-main event. MacDonald hopes the performance leads him to an opportunity to claim space alongside Johnson in the UFC champion's club.